1. Field of the Invention
This invention relates to a styrene-based resin composite material. More particularly, it relates to a styrene-based resin composite material in which a hard coating layer having high hardness and excellent adhesiveness is formed on the surface of a molding material comprising a styrene-based polymer having a syndiotactic configuration or its composition, a thermal transfer ink tape formed with a base film prepared by stretch-formed material with a styrene-based polymer or a composite composed with a lubricating heat resistant layer of curable phosphazene compound, and a magnetic recording medium having a curable phosphazene compound formed with a binder of magnetic layer and a lubricating layer on a support composed of a styrene-based polymer thereof.
2. Description of the Related Arts
A styrene-based polymer having a syndiotactic configuration, which is a crystalline polymer with excellent mechanical strength, heat resistance, chemical resistance, etc. compared with a styrene-based polymer having an atactic configuration so that can be used for various moldings, base films, etc. On applying these base film to the various usage, various hard-coating treatment in accordance with the surface hardness, lubricity and resistance to solvents of this material which is expected to each usage, has been considered.
Hard coating materials known heretofore are acrylic and silicone types. Among these, the acrylic type hard coating material can rather easily form a coating layer by irradiation of ultraviolet rays, etc. compared with others, but is insufficient in terms of adhesiveness and hardness. On the other hand, the silicone type hard coating material can form a coating layer with good adhesiveness by applying a primer treatment. However, it requires a longer curing time for heat treatment and has a migration problem, therefore, is also inadequate.
Furthermore, these hard coating materials have insufficient adhesiveness to a molded material comprising a styrene-based polymer having a syndiotactic configuration or its composition.
On the other hand, magnetic recording media such as a magnetic tape for video recorder, a magnetic tape for audio recording, a magnetic tape for computers, a magnetic disc, a magnetic drum, and a magnetic card, for which demand has been increasing in recent years, are prepared by coating a magnetic composition containing magnetic materials such as .gamma.-iron oxide onto a support such as a plastic film, disc, and card to form a magnetic layer thereon.
As the support for this purpose, a polyethylene-terephthalate (PET) film has heretofore been used, but it is insufficient in heat resistance, thus information in the medium cannot sometimes be output due to deformation of the support.
Furthermore, one of the requirements for the support for a tape is high mechanical strength. Increasing the reliability of running systems for a tape of a tape recorder, reducing the total film thickness of the tape, and accompanying higher density and narrower recording tracks, improved mechanical strength is strongly required for a tape support. Considering running properties and durability, it is particularly important that the bending strength of the tape itself be sufficient, i.e. characteristics regarding elasticities and surface hardness to decrease friction of the support itself. However, those which use the conventional PET films as a support are inadequate in terms of these characteristics and improvement thereof has been desired.
Also, a binder is added to the magnetic composition in order to adhere the magnetic material to the support. As the binder, acrylic type resins, ester type resins, epoxy type resins, urethane type resins, isocyanate type resins or silicone type resins have heretofore been known, but a magnetic layer formed by adding these binders has insufficient adhesiveness with the support, and durability and wear-resistance are also inadequate. Furthermore, it involves the defect of inferior solvent resistance.
As well as magnetic tape, there are ink ribbons which utilize the conventional polyethylene terephthalate (PET) film as a support. An ink ribbon is recognized the improvement of a characteristic from the conventional heat fusion type to the sublimation type corresponded to color printing, and the usage are expected to develop not only to the monochronous letter printing, but also Facsimile, Printing correction, a direct printing from TV and VIDEO recorders.
An ink ribbon is composed of three layers of an support (base film), ink layer and back coated layer (lublicating heat resistant layer). A back coated layer is formed in order to improve lubricity of a ribbon and prevent a damage from heat of a thermal head. Silicone type resin mainly has been used on the back coated layer, but the migration due to insufficient hardening, bad printing and bad coating on an ink layer on preparing a ribbon occurred.
The present inventors have intensively studied the subject to develop a material which can form a film or a binder layer containing magnetic materials with excellent adhesiveness, hardness, solvent resistance, wear-resistance, lubricity, etc., with one coating on a molding material or a base film comprising the above styrene-based polymer having a syndiotactic configuration.